Voluntary activation of biceps-to-triceps and deltoid-to-triceps transfers in quadriplegia

Abstract

The biceps or the posterior deltoid can be transferred to improve elbow extension function for many individuals with C5 or C6 quadriplegia. Maximum strength after elbow reconstruction is variable; the patient’s ability to voluntarily activate the transferred muscle to extend the elbow may contribute to the variability. We compared voluntary activation during maximum isometric elbow extension following biceps transfer (n = 5) and deltoid transfer (n = 6) in three functional postures. Voluntary activation was computed as the elbow extension moment generated during maximum voluntary effort divided by the moment generated with full activation, which was estimated via electrical stimulation. Voluntary activation was on average 96% after biceps transfer and not affected by posture. Individuals with deltoid transfer demonstrated deficits in voluntary activation, which differed by posture (80% in horizontal plane, 69% in overhead reach, and 70% in weight-relief), suggesting inadequate motor re-education after deltoid transfer. Overall, individuals with a biceps transfer better activated their transferred muscle than those with a deltoid transfer. This difference in neural control augmented the greater force-generating capacity of the biceps leading to increased elbow extension strength after biceps transfer (average 9.37 N-m across postures) relative to deltoid transfer (average 2.76 N-m across postures) in our study cohort.

Reduction in voluntary activation of elbow and wrist muscles in individuals with chronic hemiparetic stroke

“…A standard twitch interpolation protocol (Behm, St-Pierre, & Perez, 1996;Dowling, Konert, Ljucovic, & Andrews, 1994;Peterson et al, 2017) was used with the following specifications and modifications to optimize measurement of the paretic upper extremity. Using the locations listed in Table 4.2 as starting points, a motor point pen (Compex, Guildford, UK) was used to determine the specific location of each motor point for each muscle by finding the point where the lowest amplitude of stimulation triggered the largest visible muscle contraction (Cheong, Hong, & Chung, 2013;B.…”

“…There is no easily accessible peripheral nerve that can be stimulated to activate all of the primary elbow or wrist flexors or extensors and one must activate individual muscles through stimulation of the motor point instead. While the upper extremity anatomy presents some technical challenges, the technique has been successfully adapted following neural injuries due to spinal cord injury (Peterson et al, 2017) and multiple sclerosis (Sheean, Murray, Rothwell, Miller, & Thompson, 1997). However, to our knowledge, no one has quantified voluntary activation in the upper extremity post stroke.…”

Estimating Voluntary Activation Of The Elbow And Wrist Muscles In Chronic Hemiparetic Stroke Using Twitch Interpolation Methodology

“…A standard twitch interpolation protocol [3], [14], [15] was used with the following specifications and modifications to optimize measurement of the paretic upper extremity. Using the locations listed in Table I as starting points, a motor point pen (Compex, Guildford, UK) was used to determine the specific location of each motor point for each muscle by finding the point where the lowest amplitude of stimulation triggered the largest visible muscle contraction [16]- [18].…”

Paired pulse transcranial magnetic stimulation in the assessment of biceps voluntary activation in individuals with tetraplegia

“…A deficit in VA may result if there exists denervated muscle fibers inaccessible to voluntary drive, or suboptimal motor unit firing; both denervation and suboptimal firing affect muscle after spinal cord injury (SCI) ( Berman et al, 1996 ). Thus, non-invasive measures of VA are useful in guiding SCI rehabilitation ( Kim et al, 2015 ; Peterson et al, 2017 ). VA of a specific muscle or muscle group can be measured via peripheral nerve stimulation (VA PNS ) superimposed on an isometric maximum voluntary contraction (MVC) ( Allen et al, 1995 ; Vøllestad, 1997 ).…”

“…While VA PNS methodology can assess muscle affected by SCI ( Kim et al, 2015 ; Peterson et al, 2017 ; Jakubowski et al, 2018 ), technical challenges in measuring VA TMS exist after SCI ( Thomas et al, 1997 ) and in the assessment of other patient populations ( Todd et al, 2003 , 2016 ; Hunter et al, 2006 ; Smith et al, 2007 ; Kotan et al, 2015 ; Cadigan et al, 2017 ; Mira et al, 2017 ; Ansdell et al, 2019 ). One important limitation of VA TMS is the recruitment of muscles other than the target muscle because TMS over the motor cortex can stimulate neighboring cortical neural pathways projecting to agonistic and antagonistic muscles ( Todd et al, 2006 ).…”